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served from the cervical, dorsal, and caudal region; showing that they 
existed between all the vertebrae. The ribs are two-headed in all 
the presacral vertebrae, the atlas excepted. Here they are single- 
headed and are articulated to the first intercentrum, which shows a 
facet on each side behind, as in the Crocodilia for instance. 
In the anterior caudals the division into two heads is indicated 
by a deep groove on the posterior side of the proximal end of the 
rib. The articular faces on the centrum are located near the anterior 
end, and the capitulum sends a process towards the intercentrum. 
As stated already above all the ribs have two heads, with the 
exception of the atlas. The tuberculum articulates with the trans- 
verse process of the cervico-dorsal vertebrae, which become very strong 
and elongated in the posterior dorsal region. The capitulum is con- 
nected in the cervical region with the intercentrum and the anterior 
portion of the centrum, in the dorsal region only with the intercentrum. 
Baur’) has shown in 1886 that the ribs of Sphenodon show in 
principle the same articulation as those of the Pelycosauria. 
Of the shoulder-girdle scapula and coracoid, of the fore-limbs 
humerus, radius and ulna are preserved. No part of the pelvis was 
found, but it is well represented by other specimens in the collection. 
Of the posterior limbs femur and tibia are present. 
We shall now describe the skull. The general shape of the skull 
can best be seen from the figures. The most important fact is the 
presence of two temporal arches; an upper, postorbito-squamosal arch, 
and a lower quadratojugal arch”). There is of course also a parieto- 
quadrate arch. 
Seen from above the following openings are found in the skull. 
1) G. Baur, The Ribs of Sphenodon (Hatteria). Americ. Natural., 
November 1886, p. 979—980. 
2) In 1892 Prof. Core (On the Homologies of the Posterior Cranial 
Arches on the Reptilia, Trans. Amer. Philos. Soc., Vol. XVII, 1892, p. 15, 
Pl. II, Fig. 8) described two temporal arches in a typical Pelycosauridn 
Clepsydrops leptocephalus Corz. (Clepsydrops is very close 
to Dimetrodon.) He placed it at once in another genus Diopeus; 
and in another order the Rhynchocephalia, in the neighborhood of 
Palaeohatteria; stating that the Pelycosauria have only one 
arch, which is homologous to the zygomatic arch of Mammals, It is 
interesting to note, that the latter result was reached by Core (Fifth Contri- 
bution to the Knowledge of the Fauna of the Permian Formation of Texas 
and the Indian Territory, Proc. Amer. Philos. Soc., No. 117, 1884, p. 30 
—35, Pl. I, Fig. 1) on the identical specimen of Clepsydrops lepto- 
cephalus in 1884. 
Anat, Anz. XIII. Aufsätze, 8 
